Ryuta Kamizono

Set charset name utf8mb4 by default

3

mysql2 gem dropped testing for MySQL 5.1 which was released in Dec 2008 and already EOL in Dec 2013 at efa47a935447bb96f178c11ce32834f877c36b77. If we no longer support MySQL 5.1, utf8 (utf8mb3)...

Rails 5.2 support

2

Actually we no longer depends on activemodel-associations, but in the past this branch helped us when upgrading Rails to 5.2 so I hope it will also help for anybody.

Fix some typos

1

I've just known that the upstream of under `ext/psych/yaml/` in https://github.com/ruby/psych is libyaml. https://github.com/ruby/psych/pull/484#issuecomment-826418572